The first pool cleaner was actually designed as a cistern cleaner back in the late 1800's. A suction pump hose was attached to a crude type of hollow arm, and this was dragged over the bottom of the cistern tank to remove built-up sludge and other gunk. From there, it became a small step to adapt that technology into cleaning the bottom of swimming pools.
1939 saw the first adaption of the suction pump being attached to driving wheels on a pool cleaner to give them freedom of movement, while in1967 came the first electrically powered pool cleaner which didn't need to be attached to the filtration pump.
Today, there are three main types of automated pool cleaners available today, two of which depend on the water filtration system of your pool filter pump, and one of them which is totally robotic and wholly independent as it goes about its cleaning duties.
Automatic Pool Cleaner Types
Suction Cleaner
These are the least expensive pool cleaners and rely totally on the pool pump and filtration medium. They work simply by hooking up a hose from the pump to the unit, dropping it into the pool and letting it randomly crawl around on the bottom and up the sides of the pool. Eventually, it will make it to every part of the pool by way of its randomized movements.
A suction cleaner operates by using rotating brushes (much like a vacuum cleaner beater bar) that scrape and dislodge debris which then gets sucked into the pool filtration system. The design is upfront and basic, they’re easy to use, and obviously the least expensive, all qualities which make these units the most popular cleaners available.
Pressure Suction Cleaner
A pressure suction cleaner also employs the suction from the filter pump but also has its own built-in pump that increases the pressure within the unit. This increased suction pressure gets more of the scum and gunk off the pool bottom, and works the best on algae growth.
These units are a bit more complex, and naturally that means they’ll be a bit more expensive; however, they work better with lower rated pumps, making them a bit more flexible for any type of pool regardless of the filtration system being used.
Robotic Cleaner
These are fully programmable cleaners that use their own external power source. These are the only pool cleaner types that do not rely on the pool pump or the filtration system since they’re completely self contained.
These are the most expensive pool cleaners, and you'll need a dedicated electrical power source located outside of your pool. The cleaner is tethered by a waterproof electrical cord and they're equipped with their own filtration collection bag within. Most come with two different motors, one for the drive wheels/brushes and another for the suction pump.
If regular cleaning is done, the filter bag or canister can be emptied when the unit has finished. However, if the pool is very dirty (such as during the first cleaning of the spring) the process may have to be stopped a couple of times to empty the filter bag/canister.
Features
Bump Bars
These little bars/fenders extend slightly out and away from the main unit, telling the pool cleaner when to turn if it hits a wall or stairs. They can be activated or deactivated if you want just the bottom of the pool cleaned or you want your pool cleaner to go up the sides. The most basic automatic pool cleaners that don't have side cleaning capability rely on bump bars so they don't get stuck at a wall or in a corner.
2 Wheel Drive
Due to their smaller, compact nature, 2 wheel drive cleaners aren’t quite as efficient when it comes to cleaning a pool. These units are best suited for smaller pools and will provide a surprisingly effective amount of cleaning capability, provided dirt and debris are loose and not caked on.
4 Wheel Drive
These are the most effective and most efficient cleaners available. The 4 wheel drive system allows the use of larger and more effective brushes, the design has greater suction capability, and these particular units are better at climbing walls and stairs.
Better still are the tank tread variation attached over the wheels on premium models. This gives them extra grip on pool bottoms as well as when going up and down the sides of the pool.
Filter Bag/Canister
Robotic-style pool cleaners all have filter bags or a hard shell canister, but some have dual bags/canisters for extended cleaning chores. On more advanced units, when the first filterbag/canister fills up, the unit automatically transfers the vacuum stream to the empty one. When they both fill, the unit automatically shuts off and returns to where it started to be serviced.
Programmable Timer
Robotic pool cleaners have varying degrees of timer programmability. Basic programming allows you to program in the time you want the unit to clean, while more advanced programming allows users to punch in a daily schedule. Remote sensing capability will let you point a remote control at a specific area of the pool, and the cleaner will take care of the affected area and go back to its starting position.
What's Best for You
What's best for you depends on the type of pool you have, and to a lesser extent, on the power of your filtration pump.
Above Ground Pool
Let's make a distinction about the type of above ground pool here. The weekend fill-and-empty types don't need a pool cleaner, and they’re basically used for parties and kids so they’ll only be used on a temporary basis. They’re mostly inflatable or hard-shell plastic, and there is no connection for a filtration system of any kind.
The most common permanent type of above ground pool generally has a frame that holds up the liner. Because of this frame, side crawling suction cleaners do not work well, or they don't work at all. A basic suction cleaner which attaches to your pump hose is all you'd really need. However, most above ground pools come with pumps that aren’t very powerful, so it’s very important to get a suction pool cleaner rated for the horsepower of your pump. You can also upgrade to a higher power pump which eliminates any problems.
Of course, a pressure cleaner or a robotic cleaner would solve many of the deficiencies of a lower powered pump. The problem is these automatic pool cleaners may cost more than your pool, and although they would be excellent cleaners, the high cost may not justify their purchase.
Rectangular Below Ground Pools
Rectangular below ground pools are the easiest to clean and any type of cleaner would be suitable for use. If you clean regularly, a basic suction cleaner would be all you need, providing that your pump power is up to snuff. Pressure cleaners are a step up and meant for larger pools with the potential for algae growth, or if you simply prefer to have a heavier-duty cleaner. Robotic cleaners also work well in rectangular pools, but given their high price you might be better served to go with one or the other pump driven models.
Designer or Non-Rectangular Below Ground Pools
This is what a robotic pool cleaner is made for, and offers the best performance out of any of the other cleaner types. Since they’re not tethered to a hose, these units can move freely about the pool, easily negotiating curves and angles other pool cleaners might miss. They have less of a chance to get hung-up in a corner due to their innate directional sensing ability, and they can better navigate walls which don’t have square corners.
Can the other pool cleaners get the job done? Certainly! But afterwards, you may be out there with a manual pool cleaner to take care of the areas that they have missed. In most cases a robotic pool cleaner will clean almost every nook and cranny without you having to lift a finger.